ES2747851T3 - Relief of overtravel pressure in a gas spring - Google Patents

Abstract

A gas spring (310; 410; 510; 610) for forming equipment, comprising: a sleeve (312; 412; 512) including an axially extending side wall (320; 420; 520), an end ( 324) open, a closed end wall (322) extending transversely axially apart from the open end (324), a pressure chamber (317; 517) created in part by the side (320; 420; 520) and end walls ( 322) to receive a gas under pressure; a piston rod (316) received at least in part in the sleeve (312; 412; 512) for reciprocating movement between the extended and retracted positions; a piston rod housing (344; 544) received at least in part in the sleeve (312; 412; 512) between the piston rod (316) and the sleeve (312; 412; 512); and an overtravel pressure relief element (318; 518; 618) that includes a discharge path that is provided between the pressure chamber (317; 517) and the exterior of the spring (310; 410; 510; 610) gas and that includes a discharge duct (363; 463; 563) through the side wall (320; 420; 520) of the jacket and a gasket (362; 462; 562; 662) that hermetically covers the discharge, where the displacement of the housing (344; 544) inside the sleeve (312; 412; 512) results in the opening of the discharge path, where the relief element (318; 518; 618) overtravel pressure includes a gasket gap (360; 560) in the piston rod housing (344; 544) and houses the gasket (362; 562; 662), where the displacement of the housing (344; 544) within the sleeve results (312; 512; 612) the displacement of a part of the seal (362; 562; 662) beyond the discharge duct (363; 563) to break the seal (3 62; 562; 662).

Description

DESCRIPTION

Relief of overtravel pressure in a gas spring

Technical field

This invention relates generally to gas springs and, more particularly, to overtravel pressure relief elements in gas springs.

Background

Gas springs are well known and have been used in press molds for sheet metal stamping operations. For example, gas springs can be used as pressure pads, among many other types of applications. A conventional gas spring includes a sleeve, a piston rod housed in the sleeve, a bearing and gasket housing held in the sleeve by a retainer to guide and retain the piston rod within the sleeve and a pressure chamber to contain Gas under pressure, typically nitrogen at an operating pressure of, for example, 13.79 MPa to 34.48 MPa (2,000 to 5,000 psi) in some applications. The housing includes one or more bearings to guide the movement of the piston rod inside the sleeve, and one or more gaskets to prevent leaks from the pressure chamber. The pressurized gas deflects the piston rod into an extended position, and resists so that it can yield to movement of the piston rod from the extended position to a retracted position. But the piston rod can overturn beyond a predetermined retracted position by design, and overtravel can cause unwanted gas overpressure and other adverse conditions.

Document US 2011/0303084 A1 describes a gas cylinder actuator with an override safety device. The actuator comprises a tubular sleeve which is closed by a base provided with a gas filling valve and at the opposite end by a head part, which is provided with a hole for the passage of the stem with a piston. The gas cylinder actuator has, on the inner face of the jacket, in the compression chamber, a low relief region designed to interrupt the sealing provided by a piston seal or head part, which acts against the inner face.

Furthermore, EP 2 177783 A2 describes a safety device for gas springs. The apparatus comprises a carrier body with a space for gas formed inside, where the pressurized gas is stored by means of the filling kit. An axis moves up and down linearly within the carrier body gas space. The sealing rings, wire ring and neck bearing are placed between the main body and the operating surfaces of the shaft. Furthermore, at least one safety channel is formed on the inner surface of the carrier body and / or the outer surface of the neck bearing. The safety lift is formed to provide the outlet of the pressurized gas from the safety channel and to act through the upper surface of the neck bearing, thereby providing downward movement of the neck bearing.

Compendium

In at least one implementation, a gas spring for forming equipment includes a jacket that includes an axially extending side wall, an open end, a transversely extending closed end wall axially spaced from the open end, and a pressure created in part by the side and end walls to receive a pressurized gas. The gas spring also includes a piston rod received at least in part in the sleeve for reciprocating movement between the extended and retracted positions, and a piston rod housing received at least in part in the sleeve between the piston rod and Shirt. The gas spring further includes an overtravel pressure relief element that includes a discharge path that is disposed between the pressure chamber and the exterior of the gas spring and that includes a discharge path through the side wall of the sleeve and a gasket that tightly covers the discharge path, where displacement of the housing within the sleeve results in the opening of the discharge path.

Some objectives, features, and potential advantages of the gas spring and / or its components set forth herein include providing a device that can be easily used with a wide range of forming equipment, which easily allows the use of common components between springs of gas of different configuration and construction, that can be easily repaired and its components replaced as needed, that can be used in a wide range of applications that have different size and strength requirements, that easily adapts to a wide range of Pressure configurations, including an over-travel pressure relief element, and being relatively simple in design, inexpensive to manufacture and assemble, robust, durable, reliable and long service life in service. Of course, an apparatus embodying the present invention can achieve none, some, all, or different objectives, features, or advantages of those set forth with respect to the illustrative embodiments described herein.

Brief description of the drawings

The following detailed description of the preferred embodiments and the best mode will be set forth with respect to the accompanying drawings in which:

FIGURE 1 is a partially sectional, perspective view of a presently preferred form of a gas spring with overtravel pressure relief elements;

FIGURE 2 is an enlarged, partial sectional view of the gas spring of FIGURE 1, illustrating a piston in a normal retracted position with respect to a sleeve;

FIGURE 3 is a partial and enlarged sectional view of the gas spring of FIGURE 1 and, in contrast to FIGURE 2, illustrates the piston in an overtravel position with respect to the sleeve;

FIGURE 4 is a currently preferred sectional and partial perspective view of a gas spring with an overtravel pressure relief member, and with a multi-piece piston rod housing;

FIGURE 5 is a partial, enlarged sectional view of the gas spring of FIGURE 4, illustrating a mating arrangement between the top and bottom portions of the piston rod housing;

FIGURE 6 is an enlarged, partial sectional view of the gas spring of FIGURE 4, illustrating the housing of the piston rod;

FIGURE 7 is a further partial and enlarged sectional view of the gas spring of FIGURE 4, illustrating an overtravel condition thereof;

FIGURE 8 is an elevational and cross-sectional view of a currently preferred additional form of a gas spring with an overtravel pressure relief member, and with a multi-piece piston rod housing;

FIGURE 9 is an enlarged, partial sectional view of the gas spring of FIGURE 8, taken from the oval 9 of FIGURE 8, illustrating the housing of the piston rod;

FIGURE 10 is an enlarged, exploded view of the multi-part piston rod housing of FIGURE 8;

FIGURE 11 is a top view of another currently preferred form of a gas spring with overtravel pressure relief elements;

FIGURE 12 is a sectional view of the gas spring of FIGURE 11, taken along line 12 12 of FIGURE 11, and illustrating a piston in an advanced position relative to a sleeve;

FIGURE 13 is a sectional view similar to that of FIGURE 12 but, in contrast to FIGURE 12, illustrates the piston in a retracted and overtravel position relative to the sleeve;

FIGURE 14 is a partial sectional view of a portion of the gas spring of FIGURE 11, taken along line 14-14 of FIGURE 12;

FIGURE 15 is a partial sectional view of a currently preferred additional form of a gas spring with overtravel pressure relief elements;

FIGURE 16 is a partial sectional and perspective view of a currently preferred additional form of a gas spring with overtravel pressure relief elements;

FIGURE 17 is a partial, sectional and perspective view of a part of the gas spring of FIGURE 16; Y

FIGURE 18 is a partial, sectional and perspective view of a portion of yet another currently preferred form of a gas spring with overtravel pressure relief elements.

Detailed description of the preferred embodiments

Referring in more detail to the drawings, FIGURE 1 illustrates a gas spring 10 that can be used in forming equipment, for example, in sheet metal stamping dies and in mechanical presses (not shown). In general, the gas spring 10 may include a sleeve 12, a guide assembly 14 and gaskets housed by the sleeve 12, a piston rod 16 housed by the sleeve 12 and extending through the guide assembly 14 and sealing gaskets and having a piston plate 15 coupled thereto by fasteners, jointly operating threads or other elements, or in any suitable manner. The gas spring 10 also includes a pressure chamber 17 to contain a gas under pressure. An outer axial end of the piston rod 16 and / or plate 15 may be engageable with a die member or other part of a press or part of forming equipment (not shown).

For example, one or more of the gas springs 10 can be used in various implementations on forming equipment to provide a movable component for supporting a forming die or workpiece with an elastic force or a return force. For example, in a binder ring implementation, the gas spring 10 can provide a spring force against a binder ring of a forming die to hold a metal workpiece while another part of the forming die shapes, cuts, stretch or bend the workpiece. In an elevator implementation, the gas spring 10 can provide an elastic force and a return force to lift a workpiece off a surface of the forming die or to maintain control of the workpiece. In a cam tool implementation, the gas spring 10 can apply an elastic force to return a cam actuated tool to its initial position. Of course, the gas spring 10 can be used in a wide range of other implementations.

In accordance with the present disclosure, the gas spring 10 may include an end-of-travel or overtravel pressure relief element 18 in the event of an overtravel condition of a piece of forming equipment with which spring 10 could be used. gas. As will be discussed in more detail below, the overtravel pressure relief element 18 may be housed by the sleeve 12. Alternatively, the gas spring 10 may include a different overtravel pressure relief element 19 which may be housed by the assembly 14. Although both elements are illustrated in the drawings, it is contemplated that only one or the other can be implemented for any given gas spring.

Each of the elements 18, 19 can be in fluid communication with the pressure chamber 17 during an overtravel condition and can operate to allow the pressurized gas to be transmitted to the outside of the pressure chamber 17, to provide protection against overtravel conditions. Overtravel pressure relief elements 18, 19 normally do not allow gas from pressure chamber 17 to exit gas spring 10 in the absence of an overtravel condition associated with gas spring 10. But in the case of an overtravel condition, one or both of the overtravel pressure relief elements 18, 19 may allow the release of pressurized gas from within the pressure chamber 17 of the gas spring 10 to significantly decrease the pressure of any gas remaining in pressure chamber 17. As used herein, the term "overtravel condition" includes a condition in which a die member, or any other component of the machine with which the gas spring 10 interacts, moves beyond a position predetermined by design with respect to gas spring 10.

Referring to FIGURE 2, the sleeve 12 may include a side wall 20 that can terminate axially at a closed end 22 and at an open end 24 that receives the seal and guide assembly 14 and the piston rod 16 in the same. The pressure chamber 17 is composed at least in part of the side and end walls 20, 22 to receive a gas under pressure. The closed end 22 may be a separate component attached to the side wall 20, for example by a solder joint, or it may be entirely made of the side wall 20. The side wall 20 of the jacket 12 has an inner surface 26 defining, at least in part, the pressure chamber 17, and an outer surface 30. The sleeve 12 can generally be cylindrical in shape, for example, where at least one of the surfaces, 26, 30, interior or exterior, is cylindrical. The inner surface 26 of the side wall 20 may have a circumferential retention groove 32 constructed to receive a retainer, shown here by way of example as a split ring 34, to hold the gas spring 10 in its assembled state. To facilitate mounting and positioning of the gas spring 10 within a press, a pair of longitudinally spaced circumferential grooves 36, 38 may be machined, formed, or otherwise provided on the outer surface 30 of the sleeve 12 adjacent its ends 22 24. To receive the gas in the gas spring 10, the jacket 12 may include an inlet conduit or port 40 which may be provided through the closed end 22 of the jacket 12 in any suitable manner. Inlet port 40 may include a threaded conduit 42 for coupling a fill valve 41, eg, a Schrader valve, to sleeve 12. Closed end 22 of sleeve 12 may also include conduit 39 in fluid communication. between and with the pressure chamber 17 and the intake port 40.

Referring to FIGURE 2, the seal and guide assembly 14 may be disposed at the open end 24 of the sleeve 12 and may be hermetically coupled to the sleeve 12. The assembly 14 may include a housing 44 for the piston rod , a guide bushing 46, a stem seal 48, a stem cleaner 50, a dust cap 52 (not shown), all of which can be housed by housing 44, and a sleeve gasket 54 that can be housed by the sleeve 12 in a gasket groove 53. Guide bushing 46 may be comprised of any suitable low friction material, and may be dimensioned to slidably engage piston rod 16 to guide piston rod 16 for reciprocating axial movement within sleeve 12. Housing 44 may including a shoulder 45 on an outer surface thereof to operate in conjunction with the split ring 34, which can retain the housing 44 in the sleeve 12 so that it can be removed. The piston rod 16 is disposed, at least in part, on the sleeve 12 and through the guide and seal assembly 14 for reciprocating movement along an axis A between the extended and retracted positions on a spring cycle 10 of gas that includes a retraction stroke and an extension or return stroke. The piston rod 16 is actuated by gas from the pressure chamber 17 to divert the piston rod 16 to the extended position, and away from the retracted position. The piston rod 16 extends out of the sleeve 12 through the housing 44 of the guide assembly and sealing gaskets, and includes an outer axial end and an inner axial end provided in the sleeve 12 and which can be radially enlarged and be attachable to a portion of the piston rod housing 44 to retain the piston rod 16 in the sleeve 12. The piston rod 16 is in sealed engagement with the stem seal 48 and in sliding engagement with the piston rod cap 46 for guided relative movement between the extended and retracted positions.

The overtravel pressure relief element 18 may be a discharge plug including a plug body 60 and a plug gasket 62 housed by body 60. Element 18 may be supported by a wall discharge conduit 63 20 of the sleeve 12. The cap body 60 may include a threaded outer diameter 61 for threading into the corresponding discharge conduit 63, which may have a thread. Accordingly, the cap body 60 may also have a through conduit 64 with a countersink, which may have the characteristics of a tool to operate in conjunction with a tool (not shown), for example internal planes, for example hexagonal planes for joint operation with an Allen key or the like to install and / or remove the body 60 the cap. The body 60 of the plug may further include a stepped end 65 to house the gasket 62 of the plug. The plug gasket 62 may be an annular gasket for sealing engagement with a bottom portion or skirt 66 of the piston rod housing 44. The gasket 62 of the plug can be attached to a smooth cylindrical part of the housing 44, or to any other suitable geometric part of the housing 44 that provide good tightness. Furthermore, the axial face of the stepped end 65 of the plug body 60 can be in full circumferential contact with the housing 44. In either case, the discharge plug creates an annular and fully circumferential seal with the housing 44 which is normally fully closed, in the absence of an overtravel condition. Gasket 62 may be composed of a urethane, a nitrile, or any other suitable sealing material, and may give a value of 70-90 on a Durometer on the Shore A scale.

The alternate overtravel pressure relief element 19 may be a groove, a notch, a flattening, a reduced diameter, or any other relief in an outside diameter of the piston rod housing 44. Element 19 may include a lower end 68 that may be axially adjacent and / or overlap with a portion of gasket 54, and an upper end 69 axially spaced from lower end 68. One or both ends 68, 69 may be tapered or otherwise tapered surfaces.

Referring now to FIGURE 3, when the piston 16 has moved from a fully retracted position according to the design intent, such that the piston 16 has overturned, one or both relief elements 18, 19 allow the desired depressurization of pressure chamber 17. When the piston 16 overtravels, the piston plate 15 strikes an upper end 43 of the housing 44 to displace the housing 44 within the sleeve 12.

The overtravel pressure relief element 18 allows depressurization when the piston rod housing 44 is displaced within the sleeve 12 to the point that some recessed element of the housing 44 axially overlaps with the gasket 62 so that it weakens, cuts, or breaks the seal between gasket 62 and housing 44 to allow gas to escape between them and out of the gas spring portion 10 as indicated by horizontal arrows. In the illustrated embodiment, the recessed element includes at least bottom portion 68 of alternate element 19. In other embodiments, the recessed element may include some bottom or extension of gasket groove 53, or any other suitable surface groove, relief, or recess.

The alternate element 19 allows depressurization when the piston rod housing 44 is displaced within the sleeve 12 to the point that the bottom of the element 19 is displaced beyond a bottom of the gasket 54 so that it is weakened o Interrupts the seal between gasket 62 and housing 44 to allow gas to escape between them and out of the open end of gas spring 10 as indicated by vertical arrows in FIGURE 3.

The gas spring 10 can be mounted in any suitable way and its various components can be manufactured in any suitable way and be composed of any suitable material. For example, sleeve 12 may be transformed, drilled, drilled, threaded, and / or otherwise machined from tubes and / or solid rod material. In another example, the body 60 of the discharge plug may be constructed from, for example, steel, brass, copper, carbon fiber and / or any other suitable material.

In assembly, guide and seal assembly 14 can be preassembled, and piston rod 16 can be mounted through housing 44, and assembly 14, with stem 16 therein, can be mounted on sleeve 12 and suitably retained therein, for example by mounting the split ring 34 in the slot 32. Subsequently, the discharge plug may be screwed or otherwise coupled to the sleeve 12 until the gasket 62 seals with the accommodation 44.

In operation, and with respect to FIGURE 1, any suitable pressurizing device (not shown) can be coupled to port 40 to open valve 41 and introduce pressurized gas through port 40 into chamber 17. Once reaches the desired pressure, the pressurizing device can be retracted to allow valve 41 to settle and thus seal the pressurized gas within pressure chamber 17.

Subsequently, the gas spring 10 can be used for any suitable purpose and, in the case of an overtravel condition in which a component of the machine travels beyond a position predetermined by design with respect to the gas spring 10, the piston plate 15 strikes the outer end of the housing 44, thereby displacing the housing 44 axially within the sleeve 12, thus resulting in the breakage or loss of seating of one or more of the seals 54, 62. Such loss of Settling will allow pressurized gas from chamber 17 to escape through one or both of elements 18, 19.

FIGURES 4-7 illustrate another currently preferred form of a gas spring 110. This shape is similar in many respects to the shape of FIGURES 1-3 and similar numbers between the shapes generally designate similar or corresponding elements in all the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

Gas spring 110 includes a seal and guide assembly 114 that includes an annular stop 152 of the housing coupled to an upper end 143 of a piston rod housing 144 and trapping a cleaner 150 therebetween. The stop 152 extends the length of the housing 144 so that the housing 144 protrudes beyond the open end of sleeve 112 and can allow partial displacement of housing 144 axially within sleeve 112 where stop 152 can be stopped by retaining ring 134. The stop 152 can be coupled to the housing 144 by fasteners, threaded or with another integral fastening, welding or in any suitable way.

For example, and with respect to FIGURES 5 and 6, a retaining ring 170 may be accommodated between corresponding radially outward and inward ribs 171, 173 of housing 144 and stop 152, respectively. In addition, set screws 172 may be threaded into stop 152 and in engagement with retaining ring 170 to seat retaining ring 170 on shoulder 171 of the corresponding housing. Retaining ring 170 may be a C-shaped ring. In addition, stop 152 can house an annular joint 174 to seal assembly 114 to sleeve 112.

With reference to FIGURE 6, assembly 114 may also include a gasket 154 of the piston rod housing and a gasket reinforcement 156 that housing 144 can house in a gasket groove 153. In addition, housing 144 may include a step, a turned ring, a notch, a circumferential groove, a spiral groove, a flattening, or any other suitable undercut element 167, which may be axially adjacent and be in undercut communication with the groove Board 153. Accordingly, as illustrated in FIGURE 7, when the piston 116 has moved from a predetermined fully retracted position by design, such that the piston 116 has made an overtravel, the relief element 118 allows the desired depressurization of the spring 110 Of gas. When a die plate or other machine component and piston 116 override, the machine component strikes stop 152 to axially displace housing 144 within sleeve 112.

Relief element 118 allows depressurization when piston rod housing 144 is axially displaced within sleeve 112 to the point that housing recess element 167 is axially overlapped with plug gasket 162 so that otherwise weakens, cuts, or breaks the seal between gasket 162 and housing 144 to allow gas to escape there between and out of gas spring portion 110 through the conduit through plug 160 as indicated using the horizontal arrows in FIGURE 7.

FIGURES 8-10 illustrate another currently preferred form of a gas spring 210. This shape is similar in many respects to the shape of FIGURES 1-7 and similar numbers between the shapes generally designate similar or corresponding elements throughout the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

Gas spring 210 includes a sleeve 212, a seal and guide assembly 214 housed by the sleeve 12, a piston rod 216 housed by the sleeve 212 and extending through the guide assembly and seal 214 , and a pressure chamber 217 for containing a gas under pressure. In addition, the gas spring 210 includes an overtravel pressure relief element 218. The seal and guide assembly 214 includes a housing stop 252 that is coupled to a top end 243 of a piston rod housing 244 and traps a cleaner 250 therebetween.

Referring to FIGURES 9 and 10, stop 252 may be coupled to housing 244 by an integral coupling configuration, for example, a bayonet connection. More specifically, the stop 252 may have a generally cylindrical configuration and may include a plurality of bayonet tabs 272 extending radially inward. Similarly, the upper end 243 of the piston rod housing 244 may have a generally cylindrical configuration and may include a plurality of bayonet tabs 270 extending radially outward to operate in conjunction with the stop tabs 272. In the assembly, the stop 252 is lowered onto the upper end 243 of the housing so that the tabs 272 of the stop align with the spaces between the tabs 270 of the sleeve. The stop 252 is then rotated so that the stop tabs 272 underlie and engage the tabs 270 of the housing to lock the stop 252 onto the housing 244.

The overtravel pressure relief element 218 may be a discharge plug including a plug body 260 and a plug gasket 262 housed by body 260. Element 218 is in a discharge duct 263 of a side wall 220 of the sleeve 212. The body 260 of the plug can be coupled to the corresponding discharge conduit 263 by thread or in any other suitable way. The plug body 260 has a through conduit 264 and a sealing end 265 that houses a plug gasket 262 that engages housing 244. As indicated in FIGURE 9, the end axial face of end 265 of plug body 260 is in full circumferential contact with housing 244. In addition, housing 244 includes a recessed element 267, which may be a fully circumferential groove, as shown, or a step, a turned ring, a notch, a spiral groove, a flattening or any other suitable undercut element axially adjacent to and usually downstream of the plug body 260 and gasket 262.

In the case of an overtravel condition in which a machine component is displaced beyond a predetermined position by design with respect to the gas spring 110, the machine component strikes the stop 252, thereby axially displacing the housing 244 further into the sleeve 212, and thereby bringing the recessed element 267 into fluid communication with the through passage 264 of the plug 260 to allow the pressurized gas from chamber 217 to escape through the overtravel element 218.

FIGURES 11-14 illustrate another currently preferred form of a gas spring 310. This shape is similar in many respects to the shape of FIGURES 1-10 and similar numbers between the shapes generally designate similar or corresponding elements in all of the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

FIGURE 11 illustrates a gas spring 310 that can be used in forming equipment, for example, sheet metal stamping dies and mechanical presses (not shown). In general, the gas spring 310 may include a sleeve 312, a seal and guide assembly 314 housed by the sleeve 312, and a piston rod 316 housed by the sleeve 312 and extending through the assembly 314 of guide and sealing gaskets. Although not shown, a piston plate may be coupled to stem 316 by fasteners, co-operating threads, or other elements, or in any other suitable manner. The gas spring 310 may also include a positioner 315 housed on top of the gas spring 310 between the sleeve 312 and the seal and guide assembly 314.

Positioner 315 can be a dust cover for gas spring 310, and in any case can include a ring-shaped body 315a, and a positioning element 315b that circumferentially cuts body 315a. The positioning element 315b may include a radially outwardly protruding boss 315c received within a corresponding gap 312a of the sleeve 312, and a radially inwardly protruding boss 315d received within a corresponding gap 314a of the guide and seal assembly 314 sealing. The positioning element 315b circumferentially places the seal and guide assembly 314 with respect to the sleeve 312, for the purposes described hereinafter.

Referring to FIGURE 12, the gas spring 310 also includes a pressure chamber 317 for containing a gas under pressure. Furthermore, an external axial end of the piston rod 316 (and / or a piston plate coupled thereto), may be engageable with a die member or other part of a press or forming equipment piece (not shown).

Referring to FIGURE 12, the sleeve 312 may include a side wall 320 that can terminate axially at a closed end 322 and an open end 324 that receives the guide gasket and seal assembly 314 and the piston rod 316 in the same. Pressure chamber 317 is created at least in part by side and end walls 320, 322 to receive a gas under pressure. The closed end 322 can be a separate component attached to the side wall 320, for example by a solder joint, or it can be made entirely of the side wall 320. The side wall 320 of the sleeve 312 has an interior surface 326 defining, at least in part, the pressure chamber 317, and an exterior surface 330. Sleeve 312 may have a generally cylindrical shape, for example, where at least one of the inner or outer surfaces 326, 330 is cylindrical. The inner surface 326 of the side wall 320 may have a circumferential retention groove 332 constructed to receive a retainer, shown here by way of example as a split ring 334, to maintain the gas spring 310 in its assembled state. To facilitate mounting and positioning of gas spring 310 within a press, a pair of longitudinally spaced circumferential grooves 336, 338 may be machined, formed, or otherwise provided on outer surface 330 of jacket 312 adjacent their ends 322, 324. To receive gas within gas spring 310, jacket 312 may include an inlet conduit or port 340 which may be provided through closed end 322 of jacket 312 in any suitable manner. The inlet port 340 may include a threaded conduit 342 for coupling an accessory 341, which may include a plug or an inlet valve, for example a Schrader valve, to the sleeve 312. The closed end 322 of the sleeve 312 also it may include a conduit 339 in fluid communication between and with pressure chamber 317 and intake port 340.

Referring to FIGURE 12, the seal and guide assembly 314 may be disposed at the open end 324 of sleeve 312 and may be hermetically coupled to sleeve 312. Assembly 314 may include a piston rod housing 344 , a guide bushing 346, a stem seal 348, a stem cleaner 350, the positioner 315 and a seal 354 and a reinforcing ring 355 that can be housed by the housing 344 in a seal groove 355, all of which may be housed by housing 344 for mounting to sleeve 312. Guide bushing 346 may be comprised of any suitable low friction material, and may be dimensioned to slidably engage piston rod 316 to guide stem 316 piston for reciprocating axial movement within sleeve 312. Housing 344 may include a shoulder 345 on an outer surface thereof to operate in conjunction with the ring 334 split 334, which can retain housing 344 in sleeve 312 so that it can be removed.

The piston rod 316 is disposed, at least in part, on the sleeve 312 and through the guide and seal assembly 314 for reciprocating movement along an axis A between the extended and retracted positions on a spring cycle 310 gas that includes a retraction stroke and an extension or return stroke. The piston rod 316 is actuated by gas from the pressure chamber 317 to divert the piston rod 316 to the extended position, and away from the retracted position. Piston rod 316 extends out of sleeve 312 through housing 344 of the seal and guide assembly, and includes an outer axial end and an inner axial end provided in sleeve 312 and which can be radially enlarged and engaged with a portion of the piston rod housing 344 to retain the piston rod 316 in the sleeve 312. The piston rod 316 is in sealed engagement with the stem seal 348 and in sliding engagement with the piston rod bushing 346 for a relative guided movement between the extended and retracted positions.

Referring to FIGURE 12, the gas spring 310 may include an overshoot or overtravel pressure relief element 318 in the event of an overtravel condition of a piece of forming equipment with which the spring 310 could be used. gas. Element 318 can be in fluid communication with pressure chamber 317 during an overtravel condition and can operate to allow pressurized gas to be transmitted to the exterior of pressure chamber 317, to provide protection against overtravel conditions. The overtravel pressure relief element 318 typically does not allow gas from the pressure chamber 317 to exit the gas spring 310 in the absence of an overtravel condition associated with the gas spring 310. But in the case of an overtravel condition, the overtravel pressure relief element 318 may allow the release of pressurized gas from within the pressure chamber 317 of the gas spring 310 to thereby significantly decrease the pressure of any gas left in the pressure chamber 317. As used herein, the term "overtravel condition" includes a condition in which a die member or any other component of the machine with which the gas spring 310 interacts moves beyond a predetermined position by design with respect to gas spring 310.

Referring to FIGURES 12 and 14, the overtravel pressure relief member 318 includes a normally sealed discharge path disposed between the pressure chamber 317 and the exterior of the gas spring 310. The discharge path includes a discharge conduit 363, normally sealed, through the side wall 320 of the sleeve 312. Element 318 also includes a discharge joint 362 which is hermetically interposed with the discharge path, where the displacement of housing 344 within sleeve 312 results in opening of the discharge path. Gasket 362 can co-operate with sleeve 312 in a position at an inner end of discharge conduit 363. Element 318 may also include a joint gap 360 to house the discharge joint 362, wherein the joint gap 360 may be circular and the discharge joint 362 may be annular to seal around an inner end of conduit 363 download. For example, gasket 362 may include an annular gasket, for example an O-ring for sealing engagement with an inner surface of sleeve 312 circumferentially around discharge chute 363. In other embodiments, the gasket gap 360 may have a different shape and the discharge gasket 362 may be a solid, discrete plug of material with or without a hole therethrough. Consequently, the discharge seal 362 at least completely and circumferentially surrounds the discharge conduit 363 if it does not completely cover it, so that the discharge seal 362 provides at least a completely circumferential seal with the sleeve 312 which is normally completely closed, in the absence of an overtravel condition of the gas spring 310 resulting in a displacement of at least a portion of the seal 362 beyond the discharge conduit 363 to break the seal 362. In other words, the seal 362 is in alignment sealing with respect to the discharge conduit 363. Gasket 362 may be composed of a urethane, a nitrile, or any other suitable sealing material, and may give a value of 70-90 on a Durometer on the Shore A scale.

Referring to FIGURE 13, when the piston rod 316 has passed from a predetermined fully retracted position by design, such that the piston rod 316 has made an overtravel, the relief element 318 allows the desired depressurization of the chamber. 317 pressure. When the piston rod 316 overtravels, an upper end 343 of housing 344 is struck by a portion of the press kit (and / or a piston rod plate) to displace housing 344 within sleeve 312. The element Overtravel Pressure Relief 318 allows depressurization when the piston rod housing 344 is displaced within sleeve 312 to the point that the seal between gasket 362 and sleeve 312 is weakened, interrupted or otherwise it is broken to allow the gas to escape between them and out of the gas spring part 310. In other words, gasket 362 is displaced out of the sealing alignment with respect to discharge conduit 363.

Gas spring 310 can be mounted in any suitable manner and its various components can be manufactured in any suitable manner and be composed of any suitable material. For example, sleeve 312 can be transformed, drilled, drilled, threaded, and / or otherwise machined from tubes and / or solid bar stock. In assembly, guide and seal gasket assembly 314 can be pre-mounted, and piston rod 316 can be mounted through housing 344, and assembly 314 with piston rod 316 therein can be mounted on sleeve 312 circumferentially oriented relative thereto via positioner 315. The radially inwardly projecting protrusion is received within the corresponding recess 315d of the piston rod housing 344.

In operation, and with respect to FIGURE 12, any suitable pressurizing device (not shown) can be coupled to port 340 to open valve 41 and introduce pressurized gas through port 340 into chamber 317. Once If the desired pressure is reached, the pressurization device can be retracted to allow valve 341 to settle and thus seal the pressurized gas within pressure chamber 317.

Subsequently, the gas spring 310 can be used for any suitable purpose and, in the case of an overtravel condition in which a machine component is displaced beyond a predetermined position by design with respect to the gas spring 310, the machine component (and / or a piston plate) strikes the outer end of the housing 344, thereby displacing the housing 344 axially within the sleeve 312, and thus resulting in the break or loss of seal settlement 362. Such loss Settling will allow the pressurized gas in chamber 317 to escape through element 318.

FIGURE 15 illustrates another currently preferred form of a gas spring 410. This shape is similar in many respects to the shape of FIGURES 1-14 and similar numbers between the shapes generally designate similar or corresponding elements throughout the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

Gas spring 410 includes a sleeve 412, and a seal and guide assembly 414 housed in sleeve 412, and an overtravel pressure relief element 418 that includes portions of sleeve 412 and assembly 414. The Relief element 418 includes a discharge joint 462 housed in a gap 460 of a side wall 420 of jacket 412, and a discharge conduit 463 through side wall 420. Relief element 418 also includes a recess 467 in an outer surface of a piston rod housing 444. More particularly, recess 467 may be a notch extending circumferentially on an outside diameter of skirt 466 of housing 444. In other embodiments, recess 467 may be a slot, a flattening, a reduced diameter, a gap, a step , a turned ring, or any other relief on an outside of housing 444 of the piston rod. Under normal conditions, the recess 467 is located on the discharge joint 462 such that the discharge joint 462 is in contact with an external surface of the skirt 466 at a position below the recess 467 so as to seal the conduit 463.

In the case of an overtravel condition in which a machine component is displaced beyond a position determined by design with respect to the gas spring 410, the housing 444 is axially displaced within the sleeve 412, thereby displacing the recess 467 beyond a portion of gasket 462 in alignment or fluid communication with discharge conduit 433 to allow pressurized gas in chamber 417 to escape through overtravel relief element 418. In this embodiment, recess 467 is placed in fluid communication with an open center of gasket 462.

FIGURES 16 and 17 illustrate another currently preferred form of a gas spring 510. This shape is similar in many respects to the shape of FIGURES 1-15 and similar numbers between the shapes generally designate similar or corresponding elements in all of the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

The gas spring 510 includes a sleeve 512, and a seal and guide assembly 514 housed in the sleeve 512, and an overtravel pressure relief element 518 that includes portions of the sleeve 512 and assembly 514. The Relief element 518 includes a discharge joint 562 housed in a gap 560 of a side wall of a housing 544, and a discharge conduit 563 through a side wall 520 of sleeve 512.

The discharge joint 562 is a disc or disc-shaped joint that includes a central portion 580 having a first thickness, and a radially outer annular portion 582 that is circumferentially continuous and arranged radially outwardly from the central portion 580 and which it has a second maximum thickness greater than the first thickness. Accordingly, annular portion 582 can surround an inner or inner end of discharge conduit 563 and seal discharge conduit 563 where conduit 563 cuts an inner surface 526 of sleeve 512. In other words, gasket 562 is in alignment. sealing with respect to the discharge conduit 563. The discharge joint 562 may be circular in its outer profile, as illustrated, but may be square, oval, or any other suitable shape.

In the case of an overtravel condition in which a machine component is displaced beyond a predetermined position by design with respect to the gas spring 510, the housing 544 is displaced axially within the sleeve 512. Such displacement gives as The displacement of gasket 562 with respect to discharge conduit 563 results in such a way that a pressure chamber 517 within gas spring 510 is placed in fluid communication with the atmosphere outside spring 510 beyond a radial periphery of the gasket. 562 and through discharge conduit 563. In other words, gasket 562 is displaced out of the sealing alignment with respect to discharge conduit 563.

FIGURE 18 illustrates another currently preferred form of a gas spring 610. This shape is similar in many respects to the shape of FIGURES 1-17 and similar numbers between the shapes generally designate similar or corresponding elements in the various views of the drawing figures. Accordingly, the descriptions of the embodiments are incorporated by reference from one another in their entirety, and a description of the common subject generally cannot be repeated here.

Gas spring 610 includes a guide gasket and seal assembly 614, and an overtravel pressure relief element 618 that includes a discharge 662 gasket housed in recess 560 in side wall of housing 544. Gasket 662 discharge is a disc or disc-shaped gasket including a central solid plug or head part 680 having a first maximum thickness and a radially outer annular part 682 arranged radially outward from the central part 680 and having a second thickness less than the first thickness. Accordingly, and with reference to jacket 512 of FIGURE 16, center portion 680 can lock and seal an inner or inner end of discharge conduit 563 where conduit 563 cuts an internal surface 526 of jacket 512.

In one or more of the ways described above, an overtravel condition moves a bearing housing, the movement of which can open one or more discharge chutes through a side wall of a jacket. Such lateral discharge avoids the potentially undesirable discharge of pressurized gas from the top of the gas spring. In addition, overtravel pressure relief elements do not fail during normal use due to pressure fluctuations, for example, greater than 15-30 MPa (150-300 bar). Additionally, items are preserved during an overtravel condition to avoid any secondary hazards. In addition, the overtravel pressure relief function is configured to relieve pressure by an overtravel of the order of 0.5 to 1.5 mm, for example. The overtravel pressure relief feature enables the normal operation of a gas spring and is configured for conditioning existing products, which can also be repaired by a kit and a repair procedure for existing products. In addition, seal breakage is a non-destructive function that does not involve tearing or cutting of any fittings, so that the gas springs of the currently described embodiments can be refilled and reused without having to disassemble the gas spring to remove debris caused by overtravel condition.

It should be appreciated that one skilled in the art will recognize other embodiments encompassed within the scope of this invention. The plurality of arrangements shown and described above are merely illustrative and not a complete or exhaustive list or representation. Of course, other embodiments and implementations can still be obtained in light of this disclosure. The embodiments described above are intended to be illustrative and not limiting. The scope of the invention is defined by the following claims.

Claims (12)

1. A gas spring (310; 410; 510; 610) for forming equipment, comprising: a sleeve (312; 412; 512) including an axially extending side wall (320; 420; 520), an open end (324), a transversely spaced closed end wall (322) axially spaced from the end (324) ) open, a pressure chamber (317; 517) created in part by the side (320; 420; 520) and end (322) walls to receive a gas under pressure; a piston rod (316) received at least in part in the sleeve (312; 412; 512) for reciprocating movement between the extended and retracted positions; a piston rod housing (344; 544) received at least in part in the sleeve (312; 412; 512) between the piston rod (316) and the sleeve (312; 412; 512); Y an overtravel pressure relief element (318; 518; 618) that includes a discharge path that is disposed between the pressure chamber (317; 517) and the outside of the pressure spring (310; 410; 510; 610) gas and which includes a discharge conduit (363; 463; 563) through the side wall (320; 420; 520) of the jacket and a gasket (362; 462; 562; 662) that hermetically covers the discharge path , wherein displacement of the housing (344; 544) within the sleeve (312; 412; 512) results in the opening of the discharge path, where the overtravel pressure relief element (318; 518; 618) includes a gasket gap (360; 560) in the piston rod housing (344; 544) and houses the gasket (362; 562; 662), wherein displacement of the housing (344; 544) within the sleeve results in (312; 512; 612) the displacement of a part of the seal (362; 562; 662) beyond the conduit (363; 563) of discharge to break the seal (362; 562; 662). 2. The gas spring (410) of claim 1, wherein the overtravel pressure relief element (318) includes a gasket gap (460) in the sleeve (412) and houses the gasket (462), and wherein the piston rod housing includes a cylindrical outer surface and at least a recessed portion (467) axially adjacent to the seal (462), where displacement of the housing within the sleeve (412) results in communication of the part (467) recessed with the discharge conduit (463) to break the seal (462). 3. The gas spring (310; 410; 510; 610) of claim 1, wherein the gasket (362; 462; 562; 662) operates in conjunction with the sleeve (312; 412; 512) and with the housing in the discharge conduit (363; 463; 563). 4. The gas spring (310; 410) of claim 3, wherein the gasket (362; 462) is an annular gasket that tightly covers the discharge path at an inner end of the discharge conduit (363; 463). 5. The gas spring (510; 610) of claim 3, wherein the gasket (562; 662) is a disc gasket that tightly covers the discharge path around an inner end of the discharge conduit (563). The gas spring (510) of claim 5, wherein the disc gasket (562) includes a center portion (580) having a first thickness and a radially outer annular portion (582) arranged radially outward from the central part (580) and having a second thickness greater than the first thickness. 7. The gas spring (610) of claim 5, wherein the disc seal (662) includes a center portion (680) having a first thickness, and a radially outer annular portion (682) arranged radially outward of the central part (680) and having a second thickness less than the first thickness. 8. The gas spring (310; 410, 510; 610) of claim 1, wherein the opening of the discharge path is a non-destructible function. 9. The gas spring (310; 410; 510; 610) of claim 8, wherein the opening of the discharge path does not imply the cutting of any accessory. 10. The gas spring (310; 410; 510; 610) of claim 1, further comprising a positioner (315) disposed between the piston rod housing (344; 544) and the sleeve (312; 412; 512 ) to circumferentially position the piston rod housing (344; 544) with respect to the sleeve (312; 412; 512) to hold the seal (362; 462; 562; 662) in position with respect to the conduit (363; 463 ; 563) discharge. 11. The gas spring (310; 410; 510; 610) of claim 10, wherein the positioner (315) is part of a cover housed on top of the gas spring (310; 410; 510; 610) and includes a ring-shaped body (315a) and a positioning element (315b) that circumferentially cuts the ring-shaped body (315a). 12. The gas spring (310; 410; 510; 610) of claim 11, wherein the positioning element (315) includes a radially outwardly projecting boss (315c) received within a gap corresponding of the sleeve (312; 412; 512), and a radially inwardly projecting boss (315d) received within a corresponding recess in the piston rod housing (344; 544).